Emission rate of cloudwatch metric

To monitor the emission rate of CloudWatch metrics, you have a few options:

For metric streams specifically, CloudWatch provides a metric called MetricUpdate in the AWS/CloudWatch/MetricStreams namespace. This metric tracks the number of metric updates sent to the metric stream. You can use the Sum statistic to see the total number of metrics emitted over a period. This metric is only emitted for metric streams in the Running state.

For custom metrics, you need to understand that metrics in CloudWatch are not "created" or "deleted" as typical resources. Instead, they are data time series that get indexed when you ingest data to them. The emission rate depends on how frequently you're publishing data points to CloudWatch.

To track the emission rate of your custom metrics, you could:

1. Create a custom metric that counts the number of metrics you're publishing. For example, if you're using a Lambda function to publish metrics, you could add a counter in your code that tracks how many metrics are being sent.

2. Use CloudWatch Logs metric filters to create metrics based on log entries that indicate metric publication.

When setting up alarms to monitor metric emission rates, remember that the alarm monitoring period should be greater than or equal to the metrics resolution. For standard metrics, this is typically 60 seconds (1 minute), while high-resolution metrics can have periods as low as 10 or 30 seconds.

If you need more granular tracking of metric emission rates, you might consider using the StatsD protocol with the CloudWatch agent, which allows you to gather and aggregate metrics from your applications at customizable intervals before sending them to CloudWatch.
Sources
Monitoring your metric streams with CloudWatch metrics - Amazon CloudWatch
AWS Cloudwatch Metric | AWS re:Post
Metrics concepts - Amazon CloudWatch
Create alarms for custom metrics using Amazon CloudWatch anomaly detection - AWS Prescriptive Guidance
Retrieve custom metrics with StatsD - Amazon CloudWatch

It looks like you are describing the SampleCount statistic:

• https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Statistics-definitions.html

SampleCount is the number of data points during the period.